Answer:
171,459 particles of CO
Step-by-step explanation:
331,002,651×0.000518 = 171459
When the first number increases by one the second number is added by 4's. So from the first part to the second it added 4 then from the 2nd to the 3rd it skips adding 8 to then just add 12. Then from the 3rd to the 4th it skips adding 16 and adds 20. So the next set of numbers would be (4,64) because it skips adding the 24 and adds the 28.
Hope this helps and is not to confusing :)
So,
To divide a fraction by a fraction, all you need to do is invert the second fraction and multiply the resulting fractions.
Step 1: Flip the second fraction.

Step 2: Multiply the fractions.
First, you make 9 into a fraction which would become 36/4
then, subtract 9/4 from both sides so that would give you 3/4x = 27/4
then divide each side by 3/4 (same thing as multiply by its reciprocal) and that would give you x=9